1. Field of the Invention
The present invention relates to a one-piece metal orifice tube for a solenoid valve and a solenoid valve including a one-piece metal orifice tube.
2. Statement of the Problem
A solenoid valve comprises a valve body containing a valve mechanism. The valve mechanism regulates fluid flow between one or more inlet ports and one or more outlet ports. Consequently, the valve body includes at least one orifice that is blocked or unblocked by the valve mechanism. The valve mechanism of the solenoid valve includes an electromagnet coil and an armature. The armature moves in response to the energization and deactivation of the electromagnet coil. The armature can therefore selectively contact and unblock the orifice in order to perform the valve function.
In a prior art solenoid valve, the valve can include a tube and orifice assembly that receives the armature. An orifice component can be affixed to or formed as a part of the tube. The armature can move in a reciprocating motion in the tube and orifice assembly, wherein the armature can block and unblock the orifice when it moves in a reciprocating motion.
A prior art solenoid valve can employ two separate components to make a tube and orifice assembly. The orifice portion can include cast or machined orifice portions. However, the resulting two piece tube and orifice has disadvantages, including a larger number of components, an increased number of assembly steps or processes, a more expensive component, and a potential for leakage and/or breakage at a junction of the two piece tube and orifice assembly. The prior art two piece tube and orifice often requires heavier and/or thicker materials so that the joined assembly is sufficiently robust.
Alternatively, a prior art one-piece tube can be molded from plastic. The resulting one-piece tube and orifice may not have the leakage and/or breakage potential at a joint. However, the resulting one-piece plastic orifice tube has disadvantages, including a relatively weak overall tube, an increased brittleness and softness, and a reduced temperature capability and smaller temperature range, for example. In cases where a plastic molding process is used to form both components, the wall thickness is typically much thicker than a comparable metal tube, resulting in relatively poor magnetic performance due to a larger air gap. Yet another drawback is that a molding process produces seams or mold lines that must be removed in order that a satisfactory seal can be formed against the orifice.